Those who don't like snow? The increase would be highest in high latitudes and during the winter, reducing the effects of both latitude and seasons. It will mainly be the relatively unproductive winter seasons and polar zones that will decrease. The majority of the world's population lives in the the temperate climate zone, and that zone will increase in area since it will gain more from the subarctic or arctic zone than it will lose to the tropical zone, so it can't be all bad assuming that population density somewhat follows an idea of comfortable temperatures.

Over here at least I can with no difficulty imagine people welcoming an increase in summer temperatures from 12 to 15 °C and in winter temperatures from -8 to 0 °C. It would certainly help farmers.

You don't have to change the global climate to escape snow, you could just move...

Also, what about the hundreds of millions of people who live in areas which would be underwater with 4-degree warming? Surely more comfortable seasons for Nordic people isn't worth wiping out half of Bangladesh.

You don't have to change the global climate to escape snow, you could just move...

There's no conspiracy among frozen people to change the climate.

Quote (HarbingerDawn)

Also, what about the hundreds of millions of people who live in areas which would be underwater with 4-degree warming?

If we just replace one noun in your statement above it becomes "you don't have to change the global climate to escape the sea, you could just move".

Quote (HarbingerDawn)

Surely more comfortable seasons for Nordic people isn't worth wiping out half of Bangladesh.

Nobody is deliberately changing anything here for the sake of comfort, real estate value or ultimately habitability, and I think that's a dangerous and difficult path, which makes me somewhat sceptical towards embarking on such missions, besides the more principal side whether it is better that humans adapt to what nature throws at us or that humans adapt nature to our needs on such grand scale. All people borrow the land they live on, many just for a short time geologically. Which is particularly evident in Bangladesh and in the Nordic countries, where things can and will change in decades or a few centuries. There is time to adapt, unless perhaps if we pretend that there might be no need.

In a 4+ degree warmer world, there is a global net loss of arable land. This finding also does not account for the effects of increased extreme weather -- droughts, heat waves, etc. Food security in a warming world is an extremely big concern, as you can see if you look at those nice big charts I posted earlier, or just about any study on the agricultural and health impacts from climate change.

Quote

The majority of the world's population lives in the the temperate climate zone, and that zone will increase in area since it will gain more from the subarctic or arctic zone than it will lose to the tropical zone, so it can't be all bad assuming that population density somewhat follows an idea of comfortable temperatures.

This is again an overly simplistic statement and a failure to grasp what the broad spectrum impacts of climate change are.

Quote

There is time to adapt, unless perhaps if we pretend that there might be no need.

We can adapt to 4+ degrees of change? Sure. How big is the 'we'? For much of life on Earth it is a death sentence. For humans, it would require a massive global cooperative effort. No sign of that so far...

Choosing to allow 4+ degrees to occur is simply unethical when we have the choice of preventing it. A more rational solution would be to avoid these changes in the first place by reducing emissions. We could also try carbon sequestration and 'geoengineering', the former having less unknowns and ethical concerns.

P.S. AR4 is actually fairly dated already. Anticipate predictions of temperature rise to be shifted upwards, since we have a better understanding of feedback effects now. Also, the temperature at which various impacts become apparent have been generally shifted downward. I don't recall if IPCC has updated that yet, but PNAS (2009) has some figures.